1. Field of the Invention
The present invention relates to a wireless communication device, and more particularly, to a wireless communication device capable of switching to an external antenna module or an internal antenna module.
2. Description of the Prior Art
Currently in the development of system on chip/system in packet (SoC/SiP) technology, there are global positioning system (GPS) chipsets that integrate low noise amplifiers (LNAs). This method simplifies module wiring as the method replaces the conventional way of installing the LNA within an internal antenna module. Please refer to FIG. 1. FIG. 1 illustrates a circuit diagram of a conventional wireless communication device 10. The wireless communication device 10 can be a GPS wireless communication device. The wireless communication device 10 includes a housing 12, an internal antenna module 14, a first surface acoustic wave (SAW) filter 16, and a GPS system in packet (SiP) 18, an electric current detector 24, a switch 26, and a second surface acoustic wave filter 28. The internal antenna module 14 is installed within the housing 12 and transmits wireless communication signals. The first surface acoustic wave (SAW) filter 16 is installed within the housing and coupled to the internal antenna module 14 and filters the wireless communication signals, such as radio signals, received by the internal antenna module 14. The GPS system in packet (SiP) 18 is installed within the housing 12 and receives the wireless communication signals transmitted from the internal antenna module 14 and processes the wireless communication signals. Furthermore, the GPS SiP 18 includes a first low noise amplifier 20 and a signal processing module 22. The first low noise amplifier 20 has a signal input end 20 a that is coupled to the first surface acoustic wave filter 16 for amplifying the wireless communication signals transmitted from the first surface acoustic wave filter 16. Power required by the first noise amplifier 20 is provided by a direct current (D/C) power source Vcc_LNA through a power input end 20b. The signal processing module 22 processes the wireless communication signal, where the signal processing module 22 can include a mixer for mixing the wireless communication signal, for example mixing baseband signals with local oscillating signals to generate radio signals, or mixing radio signals with local oscillating signals to generate baseband signals. The wireless communication device 10 further includes the electric current detector 24, the switch 26 coupled to a signal output end 20c of the first low noise amplifier 20 and the electric current detector 24, and the second surface acoustic wave filter 28 installed within the housing 12 and coupled to the switch 26 and the signal processing module 22 for filtering the wireless communication signals transmitted from the switch 26 and transmitting the filtered signals to the signal processing module 22. The wireless communication device 10 can be connected to an external antenna module 30. The external antenna module 30 includes an antenna unit 32, a second low noise amplifier 34, and a capacitance C. The antenna unit 32 transmits wireless communication signals. The second low noise amplifier 34 amplifies the wireless communication signals received from the antenna unit 32. Finally, the capacitance C is installed between and coupled to the second low noise amplifier 34 and the switch 26 for blocking direct current. When the wireless communication device 10 is connected to the external antenna module 30, the electric current detector 24 can output corresponding signals to the switch 26 according to electric current change through a resistance R, because the second low noise amplifier 34 requires an inductance L to receive a direct current provided by Vcc. In other words, connecting the wireless communication device 10 to the external antenna module 30 may result in the electric current detector 24 detecting a different electric current value, and the switch 26 can determine to output the wireless communication signals transmitted from either the first low noise amplifier 20 or the second low noise amplifier 34 to the second surface acoustic wave filter 28 according to the signals transmitted from the electric current detector 24. In this way, the wireless communication device 10 can switch to the internal antenna module 14 or the external antenna module 30.
However, the complex wiring architecture of the wireless communication device 10 results in two undesired effects. First, said complex wiring causes noise and reduced efficiency on the weak GPS signal on the data transmission route. Second, the wireless communication device 10 also requires a combination of the electric current detector 24 and the switch 26 to detect whether the wireless communication device 10 is being connected to the external antenna module 30. Therefore, this creates an increase in the circuit board surface area and an increase in technical difficulty. Both of these factors led to an increase in the cost; furthermore, under the situation where the wireless communication device 10 utilizes the external antenna module 30, the first low noise amplifier 20 within the GPS SiP 18 continues to receive power from the Vcc_LNA. This causes additional power consumption.